Most motor vehicles comprise a grille defining an air inlet. The majority of the air passing through the air inlet then passes through the fins of a radiator located behind the grille to cool down the coolant inside the radiator, which in turn keeps the engine cool.
However, during certain driving conditions, there is more air passing through the air inlet than is needed to keep the engine cool. Moreover, that excess of air passing through can add significant aerodynamic drag to the car, increasing the amount of fuel used by the car.
To adapt the amount of air passing through to reach the radiator, motor vehicles can now be equipped with active grille shutters mounted on a frame between the grille and the engine or forming the grille itself. The shutters are, for example, moveable in rotation around vertical or transversal axes of the frame to limit the amount of air passing through the shutters and subsequently reaching the engine.
However, sometimes air coming from the air inlet does not directly reach the whole surface of the radiator. The radiator, for example, may be larger than the air inlet. In that case, air coming from the air inlet will mostly reach the centre of the radiator, and only a portion of the radiator will be used to cool down the coolant. The radiator is therefore not used in an efficient way. In this case, the shutters are not used to optimize the flow of air in order to use efficiently the radiator.